github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443: v3.ResourceLocator_ExactContext

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify github.com/cncf/xds/go/xds/core/v3.ResourceLocator_ExactContext in pkg:golang/github.com/cncf/xds/go@v0.0.0-20250501225837-2ac532fd4443
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/cncf/xds/go@v0.0.0-20250501225837-2ac532fd4443
Demonstrate these symbols/APIs:
  - github.com/cncf/xds/go/xds/core/v3.ResourceLocator_ExactContext

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:748c8f12c5eef9bad9c621c813b4b40a2496e794b534e6cdbe3cfd73f54735a9","contract":["ResourceLocator initializes with ResourceLocator_ExactContext containing context parameters and passes protobuf serialization and validation"],"goal":"verify github.com/cncf/xds/go/xds/core/v3.ResourceLocator_ExactContext in pkg:golang/github.com/cncf/xds/go@v0.0.0-20250501225837-2ac532fd4443","kind":"HOW","packages":["pkg:golang/github.com/cncf/xds/go@v0.0.0-20250501225837-2ac532fd4443"],"schemaVersion":1,"symbols":["github.com/cncf/xds/go/xds/core/v3.ResourceLocator_ExactContext"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/cncf/xds/go@v0.0.0-20250501225837-2ac532fd4443"],"schemaVersion":1,"subject":"pkg:golang/github.com/cncf/xds/go@v0.0.0-20250501225837-2ac532fd4443","symbols":["github.com/cncf/xds/go/xds/core/v3.ResourceLocator_ExactContext"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require (
	github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443
	google.golang.org/protobuf v1.36.12
)

require github.com/envoyproxy/protoc-gen-validate v1.3.0 // indirect

github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443 h1:aQ3y1lwWyqYPiWZThqv1aFbZMiM9vblcSArJRf2Irls=
github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443/go.mod h1:W+zGtBO5Y1IgJhy4+A9GOqVhqLpfZi+vwmdNXUehLA8=
github.com/cncf/xds/go v0.0.0-20260202195803-dba9d589def2 h1:aBangftG7EVZoUb69Os8IaYg++6uMOdKK83QtkkvJik=
github.com/cncf/xds/go v0.0.0-20260202195803-dba9d589def2/go.mod h1:qwXFYgsP6T7XnJtbKlf1HP8AjxZZyzxMmc+Lq5GjlU4=
github.com/envoyproxy/protoc-gen-validate v1.3.0 h1:TvGH1wof4H33rezVKWSpqKz5NXWg5VPuZ0uONDT6eb4=
github.com/envoyproxy/protoc-gen-validate v1.3.0/go.mod h1:HvYl7zwPa5mffgyeTUHA9zHIH36nmrm7oCbo4YKoSWA=
github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
google.golang.org/protobuf v1.36.12 h1:pJOKDDOyeXErUroCihFAd5LQuwXBSpVnKGrj5o/fwxc=
google.golang.org/protobuf v1.36.12/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=

{
  "schemaVersion": 1,
  "goal": "verify github.com/cncf/xds/go/xds/core/v3.ResourceLocator_ExactContext in pkg:golang/github.com/cncf/xds/go@v0.0.0-20250501225837-2ac532fd4443",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/cncf/xds/go@v0.0.0-20250501225837-2ac532fd4443"
  ],
  "symbols": [
    "github.com/cncf/xds/go/xds/core/v3.ResourceLocator_ExactContext"
  ]
}

package main

import (
	"fmt"

	v3 "github.com/cncf/xds/go/xds/core/v3"
	"google.golang.org/protobuf/proto"
)

func main() {
	params := &v3.ContextParams{
		Params: map[string]string{
			"env":     "staging",
			"service": "cart",
		},
	}

	exactContext := &v3.ResourceLocator_ExactContext{
		ExactContext: params,
	}

	locator := &v3.ResourceLocator{
		Scheme:                v3.ResourceLocator_XDSTP,
		Id:                    "cart-cluster",
		Authority:             "example.com",
		ResourceType:          "type.googleapis.com/envoy.config.cluster.v3.Cluster",
		ContextParamSpecifier: exactContext,
	}

	if locator.GetScheme() != v3.ResourceLocator_XDSTP {
		panic("expected XDSTP scheme")
	}
	if locator.GetId() != "cart-cluster" {
		panic("expected id cart-cluster")
	}
	if locator.GetAuthority() != "example.com" {
		panic("expected authority example.com")
	}

	gotExact := locator.GetExactContext()
	if gotExact == nil {
		panic("expected non-nil ExactContext from locator")
	}
	if gotExact.GetParams()["env"] != "staging" {
		panic("expected param env=staging")
	}
	if gotExact.GetParams()["service"] != "cart" {
		panic("expected param service=cart")
	}

	switch spec := locator.GetContextParamSpecifier().(type) {
	case *v3.ResourceLocator_ExactContext:
		if spec.ExactContext == nil || spec.ExactContext.GetParams()["service"] != "cart" {
			panic("unexpected ExactContext in ContextParamSpecifier")
		}
	default:
		panic("expected *v3.ResourceLocator_ExactContext")
	}

	data, err := proto.Marshal(locator)
	if err != nil {
		panic(fmt.Sprintf("failed to marshal ResourceLocator: %v", err))
	}

	unmarshaled := &v3.ResourceLocator{}
	if err := proto.Unmarshal(data, unmarshaled); err != nil {
		panic(fmt.Sprintf("failed to unmarshal ResourceLocator: %v", err))
	}

	unmarshaledExact := unmarshaled.GetExactContext()
	if unmarshaledExact == nil {
		panic("expected non-nil ExactContext after unmarshal")
	}
	if unmarshaledExact.GetParams()["env"] != "staging" || unmarshaledExact.GetParams()["service"] != "cart" {
		panic("mismatched parameters after unmarshal")
	}

	if err := locator.ValidateAll(); err != nil {
		panic(fmt.Sprintf("validation failed: %v", err))
	}

	fmt.Println("PASS: ResourceLocator_ExactContext verified")
}